1. Field of the Invention
This invention concerns seismic surveying in general, and more specifically it concerns a method for improving the signal-to-noise ratio of seismic reflection type procedures.
2. Description of the Prior Art
In the field of seismic surveying in general, there have been numerous proposals and arrangements for obtaining better records. These have included a large number of different types of approach. The type of seismic surveying to which the subject application applies is known as reflection surveying. In that type of seismic surveying, there have been various suggestions for attempting to improve the results. For example, there is a U.S. Pat. No. 3,622,970 to Leon Sayous, et al that was patented Nov. 23, 1971. However, that patent deals with a system which employs auto-correlation of the signals involved. And, consequently it is not relevant to the applicant's invention.
Another prior patent is U.S. Pat. No. 4,170,002 to Booth B. Strange, issued Oct. 2, 1979. That patent concerns the use of several seismic accoustic sources which are selected from different genera of seismic energy source generators and are combined to make a single array. Furthermore, these sources are fired substantially simultaneously in order to obtain a single composit seismic wave. Thus the source signal blends together the different characteristics. On the other hand, the applicant makes use of a procedure which records a plurality of seismic source generations that are detonated in series with time intervals between. The resulting signals are recorded on a single record having sufficient time duration, and the record is processed thereafter.
Another prior patent is U.S. Pat. No. 3,602,878 to Sullivan patented Aug. 31, 1971. In that case, the procedure employed involves firing a plurality of air guns at different times but so related to one another as to enhance the accoustic wave oscillation characteristics. Its results are accomplished since the air guns are ones having different volume capacities, and the enhancement provides a particular seismic energy output. In contrast, the applicant is generating a series of seismic signals with time intervals therebetween. But, the applicant's arrangement is such that each one of the seismic signals is generated at the same location as all of the others. Then, after a single record has been taken of all of the signals generated, the result is processed in a manner so as to improve the signal-to-noise ratio.